aboutsummaryrefslogtreecommitdiffstats
path: root/Game/Code/Classes/UAudioDecoder_FFMpeg.pas
blob: 18d6c03b9b66b808ad8dd16e4c29f46df1c24517 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
unit UAudioDecoder_FFMpeg;

(*******************************************************************************

This unit is primarily based upon -
    http://www.dranger.com/ffmpeg/ffmpegtutorial_all.html

    and tutorial03.c

    http://www.inb.uni-luebeck.de/~boehme/using_libavcodec.html

*******************************************************************************)

interface

{$IFDEF FPC}
  {$MODE Delphi}
{$ENDIF}

{$I switches.inc}

//{$DEFINE DebugFFMpegDecode}

uses
  Classes,
  SysUtils,
  UMusic;

implementation

uses
  UIni,
  UMain,
  avcodec,     // FFMpeg Audio file decoding
  avformat,
  avutil,
  avio,        // used for url_ferror
  mathematics, // used for av_rescale_q
  SDL,
  ULog,
  UConfig;

type
  PPacketQueue = ^TPacketQueue;
  TPacketQueue = class
    private
      firstPkt,
      lastPkt    : PAVPacketList;
      nbPackets  : integer;
      size       : integer;
      mutex      : PSDL_Mutex;
      cond       : PSDL_Cond;
      quit       : boolean;

    public
      constructor Create();
      destructor Destroy(); override;

      function Put(pkt : PAVPacket): integer;
      function Get(var pkt: TAVPacket; block: boolean): integer;
      procedure Flush();
  end;

const
  MAX_AUDIOQ_SIZE = (5 * 16 * 1024);

var
  EOFPacket:   TAVPacket;
  FlushPacket: TAVPacket;

type
  PAudioBuffer = ^TAudioBuffer;
  TAudioBuffer = array[0 .. (AVCODEC_MAX_AUDIO_FRAME_SIZE * 3 div 2)-1] of byte;

type
  TFFMpegDecodeStream = class(TAudioDecodeStream)
    private
      _EOF: boolean; // end-of-stream flag
      _EOF_lock : PSDL_Mutex;

      internalLock : PSDL_Mutex;
      resumeCond   : PSDL_Cond;

      quitRequest : boolean;

      seekRequest: boolean;
      seekFlags  : integer;
      seekPos    : int64;

      parseThread: PSDL_Thread;
      packetQueue: TPacketQueue;

      formatInfo : TAudioFormatInfo;

      // FFMpeg internal data
      pFormatCtx     : PAVFormatContext;
      pCodecCtx      : PAVCodecContext;
      pCodec         : PAVCodec;
      ffmpegStreamIndex : Integer;
      ffmpegStream      : PAVStream;

      // state-vars for DecodeFrame
      pkt             : TAVPacket;
      audio_pkt_data  : PChar;
      audio_pkt_size  : integer;

      // state-vars for AudioCallback
      audio_buf_index : cardinal;
      audio_buf_size  : cardinal;
      audio_buf       : TAudioBuffer;

      procedure Lock(); {$IFDEF HasInline}inline;{$ENDIF}
      procedure Unlock(); {$IFDEF HasInline}inline;{$ENDIF}
      function GetLockMutex(): PSDL_Mutex; {$IFDEF HasInline}inline;{$ENDIF}

      procedure ParseAudio();
      function DecodeFrame(var buffer: TAudioBuffer; bufSize: integer): integer;
      procedure SetEOF(state: boolean);
    public
      constructor Create(pFormatCtx: PAVFormatContext;
                         pCodecCtx: PAVCodecContext; pCodec: PAVCodec;
                         ffmpegStreamID : Integer; ffmpegStream: PAVStream);
      destructor Destroy(); override;

      procedure Close();                     override;

      function GetLength(): real;            override;
      function GetAudioFormatInfo(): TAudioFormatInfo; override;
      function GetPosition: real;            override;
      procedure SetPosition(Time: real);     override;
      function IsEOF(): boolean;             override;

      function ReadData(Buffer: PChar; BufSize: integer): integer; override;
  end;

type
  TAudioDecoder_FFMpeg = class( TInterfacedObject, IAudioDecoder )
    private
      class function FindAudioStreamIndex(pFormatCtx : PAVFormatContext): integer;
    public
      function GetName: String;

      function InitializeDecoder(): boolean;
      function Open(const Filename: string): TAudioDecodeStream;
  end;

function DecodeThreadMain(streamPtr: Pointer): integer; cdecl; forward;

var
  singleton_AudioDecoderFFMpeg : IAudioDecoder;


{ TFFMpegDecodeStream }

constructor TFFMpegDecodeStream.Create(pFormatCtx: PAVFormatContext;
                   pCodecCtx: PAVCodecContext; pCodec: PAVCodec;
                   ffmpegStreamID : Integer; ffmpegStream: PAVStream);
begin
  inherited Create();

  packetQueue := TPacketQueue.Create();

  audio_pkt_data := nil;
  audio_pkt_size := 0;

  audio_buf_index := 0;
  audio_buf_size  := 0;

  FillChar(pkt, sizeof(TAVPacket), 0);

  Self.pFormatCtx := pFormatCtx;
  Self.pCodecCtx := pCodecCtx;
  Self.pCodec    := pCodec;
  Self.ffmpegStreamIndex := ffmpegStreamIndex;
  Self.ffmpegStream      := ffmpegStream;

  formatInfo := TAudioFormatInfo.Create(
    pCodecCtx^.channels,
    pCodecCtx^.sample_rate,
    // pCodecCtx^.sample_fmt not yet used by FFMpeg -> use FFMpeg's standard format
    asfS16
  );

  _EOF := false;
  _EOF_lock := SDL_CreateMutex();

  internalLock := SDL_CreateMutex();
  resumeCond := SDL_CreateCond();

  parseThread := SDL_CreateThread(@DecodeThreadMain, Self);
end;

destructor TFFMpegDecodeStream.Destroy();
begin
  Close();
  inherited;
end;

procedure TFFMpegDecodeStream.Close();
var
  status: integer;
begin
  Lock();
  quitRequest := true;
  SDL_CondSignal(resumeCond);
  Unlock();

  if (parseThread <> nil) then
  begin
    SDL_WaitThread(parseThread, status);
  end;

  // Close the codec
  if (pCodecCtx <> nil) then
  begin
    avcodec_close(pCodecCtx);
    pCodecCtx := nil;
  end;

  // Close the video file
  if (pFormatCtx <> nil) then
  begin
    av_close_input_file(pFormatCtx);
    pFormatCtx := nil;
  end;

  FreeAndNil(packetQueue);
  FreeAndNil(formatInfo);
end;

procedure TFFMpegDecodeStream.Lock();
begin
  SDL_mutexP(internalLock);
end;

procedure TFFMpegDecodeStream.Unlock();
begin
  SDL_mutexV(internalLock);
end;

function TFFMpegDecodeStream.GetLockMutex(): PSDL_Mutex;
begin
  Result := internalLock;
end;

function TFFMpegDecodeStream.GetLength(): real;
begin
  Result := pFormatCtx^.duration / AV_TIME_BASE;
end;

function TFFMpegDecodeStream.GetAudioFormatInfo(): TAudioFormatInfo;
begin
  Result := formatInfo;
end;

function TFFMpegDecodeStream.IsEOF(): boolean;
begin
  SDL_mutexP(_EOF_lock);
  Result := _EOF;
  SDL_mutexV(_EOF_lock);
end;

procedure TFFMpegDecodeStream.SetEOF(state: boolean);
begin
  SDL_mutexP(_EOF_lock);
  _EOF := state;
  SDL_mutexV(_EOF_lock);
end;

function TFFMpegDecodeStream.GetPosition(): real;
var
  bytes: integer;
begin
  // see: tutorial on synching (audio-clock)
  Result := 0;
end;

procedure TFFMpegDecodeStream.SetPosition(Time: real);
var
  bytes:    integer;
begin
  Lock();
  seekPos := Trunc(Time * AV_TIME_BASE);
  // FIXME: seek_flags = rel < 0 ? AVSEEK_FLAG_BACKWARD : 0
  seekFlags := 0;//AVSEEK_FLAG_BACKWARD;
  seekRequest := true;
  SDL_CondSignal(resumeCond);
  Unlock();
end;

function DecodeThreadMain(streamPtr: Pointer): integer; cdecl;
var
  stream: TFFMpegDecodeStream;
begin
  stream := TFFMpegDecodeStream(streamPtr);
  stream.ParseAudio();
  result := 0;
end;

procedure TFFMpegDecodeStream.ParseAudio();
var
  packet: TAVPacket;
  seekTarget: int64;
  eofState: boolean;
  pbIOCtx: PByteIOContext;
begin
  eofState := false;

  while (true) do
  begin
    Lock();
    // wait if end-of-file reached
    if (eofState) then
    begin
      if (not (seekRequest or quitRequest)) then
      begin
        // signal end-of-file
        packetQueue.put(@EOFPacket);
        // wait for reuse or destruction of stream
        repeat
          SDL_CondWait(resumeCond, GetLockMutex());
        until (seekRequest or quitRequest);
      end;
      eofState := false;
      SetEOF(false);
    end;

    if (quitRequest) then
    begin
      break;
    end;

    // handle seek-request
    if(seekRequest) then
    begin
      // TODO: Do we need this?
      //       The position is converted to AV_TIME_BASE and then to the stream-specific base.
      //       Why not convert to the stream-specific one from the beginning.
      seekTarget := av_rescale_q(seekPos, AV_TIME_BASE_Q, ffmpegStream^.time_base);
      if(av_seek_frame(pFormatCtx, ffmpegStreamIndex,
          seekTarget, seekFlags) < 0) then
      begin
        // this will crash in FPC due to a bug
        //Log.LogStatus({pFormatCtx^.filename +} ': error while seeking', 'UAudioDecoder_FFMpeg');
      end
      else
      begin
        packetQueue.Flush();
        packetQueue.Put(@FlushPacket);
      end;
      seekRequest := false;
    end;

    Unlock();

    
    if(packetQueue.size > MAX_AUDIOQ_SIZE) then
    begin
      SDL_Delay(10);
      continue;
    end;

    if(av_read_frame(pFormatCtx, packet) < 0) then
    begin
      // check for end-of-file (eof is not an error)
      {$IF (LIBAVFORMAT_VERSION_MAJOR >= 52)}
      pbIOCtx := pFormatCtx^.pb;
      {$ELSE}
      pbIOCtx := @pFormatCtx^.pb;
      {$IFEND}
      
      if(url_feof(pbIOCtx) <> 0) then
      begin
        {$IFDEF DebugFFMpegDecode}
        SafeWriteLn('feof');
        {$ENDIF}
        eofState := true;
        continue;
      end;

      // check for errors
      if(url_ferror(pbIOCtx) = 0) then
      begin
        {$IFDEF DebugFFMpegDecode}
        SafeWriteLn('Errorf');
        {$ENDIF}
        // no error -> wait for user input
        SDL_Delay(100);
        continue;
      end
      else
      begin
        // an error occured -> abort
        // TODO: eof or quit?
        eofState := true;
        continue;
      end;
    end;

    //SafeWriteLn( 'ffmpeg - av_read_frame' );

    if(packet.stream_index = ffmpegStreamIndex) then
    begin
      //SafeWriteLn( 'packet_queue_put' );
      packetQueue.put(@packet);
    end
    else
    begin
      av_free_packet(@packet);
    end;
  end;
end;

function TFFMpegDecodeStream.DecodeFrame(var buffer: TAudioBuffer; bufSize: integer): integer;
var
  len1,
  data_size: integer;
begin
  result := -1;

  if EOF then
    exit;

  while(true) do
  begin
    while (audio_pkt_size > 0) do
    begin
      //SafeWriteLn( 'got audio packet' );
      data_size := bufSize;

      {$IF LIBAVCODEC_VERSION >= 51030000} // 51.30.0
      len1 := avcodec_decode_audio2(pCodecCtx, @buffer,
                  data_size, audio_pkt_data, audio_pkt_size);
      {$ELSE}
      // FIXME: with avcodec_decode_audio a package could contain several frames
      //        this is not handled yet
      len1 := avcodec_decode_audio(pCodecCtx, @buffer,
                  data_size, audio_pkt_data, audio_pkt_size);
      {$IFEND}

      //SafeWriteLn('avcodec_decode_audio : ' + inttostr( len1 ));

      if(len1 < 0) then
      begin
        // if error, skip frame
        {$IFDEF DebugFFMpegDecode}
        SafeWriteLn( 'Skip audio frame' );
        {$ENDIF}
        audio_pkt_size := 0;
        break;
      end;

      Inc(audio_pkt_data, len1);
      Dec(audio_pkt_size, len1);

      if (data_size <= 0) then
      begin
        // no data yet, get more frames
        continue;
      end;

      // we have data, return it and come back for more later
      result := data_size;
      exit;
    end;

    if (pkt.data <> nil) then
    begin
      av_free_packet(@pkt);
    end;

    if (packetQueue.quit) then
      exit;

    if (packetQueue.Get(pkt, true) < 0) then
      exit;

    audio_pkt_data := PChar(pkt.data);
    audio_pkt_size := pkt.size;

    if (audio_pkt_data = PChar(FlushPacket.data)) then
    begin
      avcodec_flush_buffers(pCodecCtx);
      {$IFDEF DebugFFMpegDecode}
      SafeWriteLn('Flush');
      {$ENDIF}
      continue;
    end;

    // check for end-of-file
    if (audio_pkt_data = PChar(EOFPacket.data)) then
    begin
      // end-of-file reached -> set EOF-flag
      SetEOF(true);
      {$IFDEF DebugFFMpegDecode}
      SafeWriteLn('EOF');
      {$ENDIF}
      // note: buffer is not (even partially) filled -> no data to return
      exit;
    end;

    //SafeWriteLn( 'Audio Packet Size - ' + inttostr(audio_pkt_size) );
  end;
end;

function TFFMpegDecodeStream.ReadData(Buffer : PChar; BufSize: integer): integer;
var
  outStream       : TFFMpegDecodeStream;
  len1,
  audio_size      : integer;
  len             : integer;
begin
  len := BufSize;
  result := -1;

  // end-of-file reached
  if EOF then
    exit;

  while (len > 0) do begin
    if (audio_buf_index >= audio_buf_size) then
    begin
      // we have already sent all our data; get more
      audio_size := DecodeFrame(audio_buf, sizeof(TAudioBuffer));
      //SafeWriteLn('audio_decode_frame : '+ inttostr(audio_size));

      if(audio_size < 0) then
      begin
        // if error, output silence
        audio_buf_size := 1024;
        FillChar(audio_buf, audio_buf_size, #0);
        //SafeWriteLn( 'Silence' );
      end
      else
      begin
        audio_buf_size := audio_size;
      end;
      audio_buf_index := 0;
    end;

    len1 := audio_buf_size - audio_buf_index;
    if (len1 > len) then
      len1 := len;

    Move(audio_buf[audio_buf_index], Buffer[0], len1);

    Dec(len, len1);
    Inc(Buffer, len1);
    Inc(audio_buf_index, len1);
  end;

  result := BufSize;
end;


{ TAudioDecoder_FFMpeg }

function TAudioDecoder_FFMpeg.GetName: String;
begin
  result := 'FFMpeg_Decoder';
end;

function TAudioDecoder_FFMpeg.InitializeDecoder: boolean;
begin
  //Log.LogStatus('InitializeDecoder', 'UAudioDecoder_FFMpeg');

  av_register_all();

  // init end-of-file package
  av_init_packet(EOFPacket);
  EOFPacket.data := Pointer(PChar('EOF'));

  // init flush package
  av_init_packet(FlushPacket);
  FlushPacket.data := Pointer(PChar('FLUSH'));

  result := true;
end;

class function TAudioDecoder_FFMpeg.FindAudioStreamIndex(pFormatCtx : PAVFormatContext): integer;
var
  i : integer;
  streamIndex: integer;
  stream : PAVStream;
begin
  // find the first audio stream
  streamIndex := -1;

  for i := 0 to pFormatCtx^.nb_streams-1 do
  begin
    //Log.LogStatus('aFormatCtx.streams[i] : ' + inttostr(i), 'UAudio_FFMpeg');
    stream := pFormatCtx^.streams[i];

    if ( stream.codec^.codec_type = CODEC_TYPE_AUDIO ) then
    begin
      //Log.LogStatus('Found Audio Stream', 'UAudio_FFMpeg');
      streamIndex := i;
      break;
    end;
  end;

  result := streamIndex;
end;

function TAudioDecoder_FFMpeg.Open(const Filename: string): TAudioDecodeStream;
var
  pFormatCtx     : PAVFormatContext;
  pCodecCtx      : PAVCodecContext;
  pCodec         : PAVCodec;
  ffmpegStreamID : Integer;
  ffmpegStream   : PAVStream;
  wanted_spec,
  csIndex        : integer;
  stream         : TFFMpegDecodeStream;
begin
  result := nil;

  if (not FileExists(Filename)) then
  begin
    Log.LogStatus('LoadSoundFromFile: Sound not found "' + Filename + '"', 'UAudio_FFMpeg');
    exit;
  end;

  // open audio file
  if (av_open_input_file(pFormatCtx, PChar(Filename), nil, 0, nil) > 0) then
    exit;

  // retrieve stream information
  if (av_find_stream_info(pFormatCtx) < 0) then
    exit;

  {$IFDEF DebugFFMpegDecode}
  dump_format(pFormatCtx, 0, pchar(Filename), 0);
  {$ENDIF}

  ffmpegStreamID := FindAudioStreamIndex(pFormatCtx);
  if (ffmpegStreamID < 0) then
    exit;

  //Log.LogStatus('AudioStreamIndex is: '+ inttostr(ffmpegStreamID), 'UAudio_FFMpeg');

  ffmpegStream := pFormatCtx.streams[ffmpegStreamID];
  pCodecCtx := ffmpegStream^.codec;

  pCodec := avcodec_find_decoder(pCodecCtx^.codec_id);
  if (pCodec = nil) then
  begin
    Log.LogStatus('Unsupported codec!', 'UAudio_FFMpeg');
    exit;
  end;

  avcodec_open(pCodecCtx, pCodec);
  //WriteLn( 'Opened the codec' );

  stream := TFFMpegDecodeStream.Create(pFormatCtx, pCodecCtx, pCodec,
              ffmpegStreamID, ffmpegStream);

  result := stream;
end;


{ TPacketQueue }

constructor TPacketQueue.Create();
begin
  inherited;

  firstPkt := nil;
  lastPkt  := nil;
  nbPackets := 0;
  size := 0;

  mutex := SDL_CreateMutex();
  cond  := SDL_CreateCond();
end;

destructor TPacketQueue.Destroy();
begin
  Flush();
  SDL_DestroyMutex(mutex);
  SDL_DestroyCond(cond);
  inherited;
end;

function TPacketQueue.Put(pkt : PAVPacket): integer;
var
  pkt1 : PAVPacketList;
begin
  result := -1;

  if ((pkt <> @EOFPacket) and (pkt <> @FlushPacket)) then
    if (av_dup_packet(pkt) < 0) then
      exit;

  pkt1 := av_malloc(sizeof(TAVPacketList));
  if (pkt1 = nil) then
    exit;

  pkt1^.pkt  := pkt^;
  pkt1^.next := nil;


  SDL_LockMutex(Self.mutex);
  try

    if (Self.lastPkt = nil) then
      Self.firstPkt := pkt1
    else
      Self.lastPkt^.next := pkt1;

    Self.lastPkt := pkt1;
    inc(Self.nbPackets);

    //SafeWriteLn('Put: ' + inttostr(nbPackets));

    Self.size := Self.size + pkt1^.pkt.size;
    SDL_CondSignal(Self.cond);

  finally
    SDL_UnlockMutex(Self.mutex);
  end;

  result := 0;
end;

function TPacketQueue.Get(var pkt: TAVPacket; block: boolean): integer;
var
  pkt1 : PAVPacketList;
begin
  result := -1;

  SDL_LockMutex(Self.mutex);
  try
    while true do
    begin
      if (quit) then
        exit;

      pkt1 := Self.firstPkt;

      if (pkt1 <> nil) then
      begin
        Self.firstPkt := pkt1.next;
        if (Self.firstPkt = nil) then
          Self.lastPkt := nil;
        dec(Self.nbPackets);

        //SafeWriteLn('Get: ' + inttostr(nbPackets));

        Self.size := Self.size - pkt1^.pkt.size;
        pkt := pkt1^.pkt;
        av_free(pkt1);

        result := 1;
        break;
      end
      else
      if (not block) then
      begin
        result := 0;
        break;
      end
      else
      begin
        SDL_CondWait(Self.cond, Self.mutex);
      end;
    end;
  finally
    SDL_UnlockMutex(Self.mutex);
  end;
end;

procedure TPacketQueue.Flush();
var
  pkt, pkt1: PAVPacketList;
begin
  SDL_LockMutex(Self.mutex);

  pkt := Self.firstPkt;
  while(pkt <> nil) do
  begin
    pkt1 := pkt^.next;
    av_free_packet(@pkt^.pkt);
    // Note: param must be a pointer to a pointer!
    av_freep(@pkt);
    pkt := pkt1;
  end;
  Self.lastPkt := nil;
  Self.firstPkt := nil;
  Self.nbPackets := 0;
  Self.size := 0;

  SDL_UnlockMutex(Self.mutex);
end;


initialization
  singleton_AudioDecoderFFMpeg := TAudioDecoder_FFMpeg.create();

  //writeln( 'UAudioDecoder_FFMpeg - Register Decoder' );
  AudioManager.add( singleton_AudioDecoderFFMpeg );

finalization
  AudioManager.Remove( singleton_AudioDecoderFFMpeg );


end.